Unitized electrode holder for electric furnace electrodes or the like

ABSTRACT

A clamping band to receive an electric furnace electrode is mounted on one end of a tubular supporting arm. A contact shoe is movable into and out of clamping engagement with electrode. An actuating tube and a bus tube are connected to the contact shoe and are mounted for longitudinal movement within the supporting arm. The bus tube is preferably disposed coaxially within the actuating tube. The contact shoe is formed with coolant passages connecting with the inside of the bus tube and the space between the bus tube and the coaxial actuating tube, so that the coolant can be circulated through the tubes and the passages. An annular fluid power cylinder is connected to the supporting arm and is mounted around the actuating tube. The cylinder includes an annular piston connected to the actuating tube. Spring means are provided to bias the contact shoe into clamping engagement with the electrode. The clamping band is also formed with coolant passageways. The supporting arm comprises an inner cylinder shell and an outer rectangular shell, with spaces therebetween to carry the coolant to and from the passageways in the clamping band.

United States Patent [72] lnventors Alfred B. Turner Pinson;

Lewis 11. Durdin, Birmingham, both of, Ala. [2-1 Appl. No. 18,465

[22] Filed [45] Patented [73] Assignee Mar. 11, 1970 Aug. 31, 1971 Dixie Bronze Company Birmingham, Ala.

[54] UNITIZED ELECTRODE HOLDER FOR ELECTRIC FURNACE ELECTRODES OR THE LIKE 14 Claims, 7 Drawing Figs.

[52] U.S.C1 13/15 [51] int. Cl 1105b 7/10, F27d 11/10 [50] Field oiSearch 13/14, 15, 16

[56] References Cited UNITED STATES PATENTS 2,148,834 2/1939 Payne 13/16 2,179,153 11/1939 Jones 13/16 2,623,080 12/1952 Young.. 13/16 2,997,511 8/1961 Turner 13/15 5/1969 Turner ABSTRACT: A clamping band to receive an electricfurnace electrode is mounted onone end of a tubular supporting arm. A contact shoe is movable into and out of clamping engagement with electrode. An actuating tube and a bus tube are connected to the contact shoe and are mounted for longitudinal movement within the supporting arm. The bus tube is preferably disposed coaxially. within the actuating tube. The contact shoe is formed with coolant passages connecting with the inside of the bus tube and the space between the bus tube and the coaxial actuating tube, so that the coolant can be circulated through the tubes and the passages. An annular fluid power cylinder is connected to the supporting arm and is mounted around the actuating tube. The cylinder includes an annular piston connected to the actuating tube. Spring means are provided to bias the contact shoe into clamping engagement with the electrode. The clamping band is also formed with coolant passageways. The supporting arm comprises an inner cylinder shell and an outer rectangular shell, with spaces therebetween to carry the coolant to and from the passageways in the clamping band.

PIATENIED meal ml 3.602.624

sum 1 or 2 N VE N TOPS Alfredfi. Turner I Lewis )1. Durdi/L aifor eys' holder for use with electric furnace electrodes or the like. The

holder provides support for the electrode and also carries electrical currents to the electrode. The holder employs clamping means which can be released so that the electrode can be slipped through the holder as the electrode is gradually consumed in the electric furnace;

One object of the present invention is to provide a new and improved electrode holder which is uniti zed in construction in that the clamping mechanism for engaging the electrode is combined in one unit with a supporting arm or mast, the clamping mechanism being mounted at the outer end of the mast.

Thus, the present invention preferably includes a clamping band adapted to receive the electrode. A contact shoe is disposed in opposition to the band for movement into and out of clamping engagement with the band. The ends of the band are welded or otherwise secured to the outer end of the supporting mast arm, which comprises an outer tubular member connected to the band. An actuating tube and a bus tube are connected to the shoe and are mounted within the outer tubular member for longitudinal movement. Preferably, the bus tube is coaxially received within the actuating tube. A fluid coolant is circulated to and from passages in the shoe, through the bus tube and the actuating tube. The contact shoe is actuated by power means, preferably in the form of an annular fluid power cylinder connected to the outer tubular member and mounted around the actuating tube. The cylinder has an annular piston connected to the actuating tube. Springs are preferably mounted within the cylinder to bias the shoe into clamping engagement with the electrode. The outer tubular member is preferably formed with a cylindrical inner shell and a rectangular outer shell, to provide spaces between the shells. Such spaces are employed to circulate the fluid coolant to and from coolant passageways formed in the clamping band. Further objects, advantages and features of the present invention will appear from the following description, taken with the accompanying drawings in which:

FIG. 1 is a plan view of a unitized electrode holder to be described as an illustrative embodiment of the present invention.

FIG. 2 is an elevational view of the contact shoe, taken generally as indicated by the line 2-2 in FIG. 1.

FIG. 3 is a vertical section taken along the line 33, shown in both FIGS. 1 and 6.

FIG. 4 is a vertical section taken along the line 4-4, shown in both FIGS. land 5.

FIG. 5 is a fragmentary elevation, partly in central longitudinal section through the clamping band and clamping shoe.

FIG. 6 is an extension of FIG. 5 and comprises a central longitudinal section taken through the actuating cylinder.

FIG. 7 is a fragmentary enlarged horizontal section, taken along the line 77 in FIG. 5. It will be seen that the drawings illustrate a unitized electrode holder 10, adapted to support a large cylindrical electric furnace electrode 12, shown in broken lines in FIGS. 1 and 5. The electrode may be as large as 24 inches in diameter, or even larger. The illustrated electrode holder 10 comprises a clamping bank 14 mounted on the outer end of a mast arm 16. The bank 14 is adapted to be received around the electrode 12. As illustrated, the mast arm 16 comprises an outer tubular member 18' to which the ends of the band 14 are welded or otherwise secured. The band 14 is preferably made of stainless steel or some other suitable material which is high in strength and resistant to the heat generated by the electric furnace. The outer tubular member 18 of the mast arm 16 may be made of steel or some other suitable material.

The electrode holder 10 also utilizes a contact shoe 20 which is disposed in opposition to the clamping bank 14 and is movable into and out of clamping engagement with the electrode 12. The shoe 20 ispreferably made of copper or some other material affording lowelectrical resistance,

As shown in FIGS. 5 and 6, the contact shoe 20 is preferably supported by an actuating tube 22 and a bus tube 24, movable longitudinally withinthe outer tubular member 18. The tubes 22and 24 are illustrated in the form of coaxial cylinders, one mounted within the other. In this case, the bus tube 24 is within the actuating tube 22. The bus tube 24 is preferably made of copper or some other material afi'ording low electrical resistance. The actuating tube 22 may be made of steel or some other material of high strength. The tubes 22 and 24 are suitably secured to the contact shoe 20. It will be seen that the actuating tube 22 is provided with a flange 26 which is secured to the contact shoe 20 by means of bolts 28 or other suitable fasteners. The bus tube 24 is illustrated as being mounted around a cylindrical stub 30 projecting from the contact shoe 20. The bus tube 24 is preferably brazed to the stub 30.

It is preferred to provide electrical insulating means between the bus tube 24 and the actuating tube 22. As shown, one or more insulting rings 32 are interposed the tubes 22 and 24. The rings 32 are retained on the bus tube 24 between outwardly projecting ridges 34. It is preferred to form one or more openings 36 through each of the rings 32, to provide for the passage of cooling water or some other fluid coolant.

Electrical insulation may also be provided between the flange 26 and the contact shoe 20, and also between the bolts 28 and the flange 26. Such insulation may be in the form of thin spacers 38 and 40.

The contact shoe 20 is preferably provided with passages through which the cooling water or other fluid coolant may flow. As shown in FIGS. 2 and 5, the shoe 20 has a rearwardly facing central opening 42 which connects with the inside of the bus tube 24, through the hollow stub 30. Cooling passages 44 radiate outwardly in the shoe 20 from the central opening 42. All of the radial passages 44 connect with an annular space 46 extending within the shoe around the margins thereof. From the marginal space 46, passages 48 extend inwardly in a radial direction to communicate with outlet openings 50. It will be seen from FIG. 5 that the openings 50 extend rearwardly out of the contact shoe 20 so as to communicate with the space between the actuating tube 22 and the bus tube 24. The openings 26 in the insulating rings 32 provide for the passage of the cooling water along the space between the tubes 22 and 24.

The contact shoe 20 is connected to one end of the bus tube 24, while the opposite end is supplied with electricity and cooling water. The electrical current is supplied by a bracket 52 to which one or more electrical cables 54 may be con nected. The bracket 52 may be brazed, welded, clamped or otherwise secured to the bus tube 24. To receive the cooling water, the bus tube 24 is provided with a fitting 56 to which a supply hose or the like may be connected. The illustrated fitting 56 is mounted in an opening 58 extending through a wall 60 which closes the end of the bus tube. It will be understood that the cooling water may be circulated in either direction through the bus tube 24 and the contact shoe 20. Thus, it is only by way of example that the cooling water is indicated as flowing into the bus tube 24 through the fitting 56.

As already indicated, the actuating tube 22 is employed for the return flow of the water or other fluid coolant. Thus, an outlet pipe 62 is connected to the actuating tube 22, at the end thereof remote from the contact shoe 20. A suitable fitting 64 is mounted on the end of the pipe 62 to receive a hose or the like. It will be understood that the circulation may be reversed so that the pipe 62 will serve as the inlet pipe.

A sealed joint 66 is provided between the end of the actuating tube 22 and the outside of the bus tube 24. Such joint 66 is illustrated as comprising a packing ring 68 clamped between flanges 70 and 72 by means of bolts 74. The flange 70 is welded or otherwise secured to the end of the actuating tube 22, while the flange 72 is secured to the flange 70 by the bolts 74. The flange 72 has an opening 76 which affords clearance around the bus tube 24. The ring 68 is compressed so as to form a seal between the tubes 22 and 24.

In this case the outer tubular member 18 of the supporting arm 16 comprises inner and outer shells 80 and 82, as shown most clearly in FIGS. 4 and S. The inner shell 80 is cylindrical while the outer shell 82 is illustrated as being rectangular in shape.

The actuating tube 22 is longitudinally slidable within the cylindrical inner shell 80. To minimize friction, rings 84 are mounted on the actuating tube 22 for sliding engagement with the inside of cylindrical shell 80. Illustrated rings 84 are retained in annular grooves 86, formed in the actuating tube 82.

In addition to stiffening the supporting arm 16, the inner and outer shells 80 and 82 provide passages 88 and 90 for the circulation of cooling water through the clamping band 14. As shown, the passages 88 and 90 are on the opposite sides of the rectangular outer shell 82. Upper and lower webs or partitions 92 are mounted between the cylindrical inner shell 80 and the rectangular outer shell 82 to separate the passages 88 and 90. Connections to the passages 88 and 90 are provided by separate pipes 94 and 96, shown in FIG. 6. The water may be circulated in either direction through the pipes 94 and 96 and the passages 88 and 90.

The contact shoe is preferably of the construction disclosed and claimed in the Turner Pat. No. 2,997,511, issued Aug. 22, 1961. Thus, the shoe 20 comprises a body 98 and a cover plate 100, welded or brazed to the body 98. The openings 42 and the radial passages 44 are formed in the body 98, preferably by a casting operation. The passages 46 and 48 and the openings 50 are also formed in the body 98. The front sides of all of these passages and openings are closed by the plate 100. It will be seen that the plate 100 is cylindrically curved for engagement with the cylindrical electrode 12.

The clamping bank 14 is preferably of the general construction disclosed and claimed in the Turner Pat. No. 3,444,305 patented May 13, 1969. Thus, the illustrated band 14 comprises inner and outer walls 102 and 104 with passages 106 therebetween, to provide for the flow of the cooling water. Upper and lower walls 108 and 110 are welded or otherwise secured between the inner and outer walls 102 and 104. The passages 106 are subdivided by partitions 112 welded or otherwise secured between the walls 102 and 104.

The band 14, is cylindrically curved to conform to the shape of the electrode 12. It will be seen that the band 14 is protected by one or more curved liner plates 114, interposed between the band and the electrode 12. The plates 114 are suitably mounted on the band 14. As shown, the plates are fitted with clips 116 adapted to hook over the upper edge of the band 114. This construction makes it easy to remove and replace the liner plates 114 as they. become worn or eroded. The liner plates 114 protect the band 14 from any significant wear or erosion. It is an easy matter to replace the liner plates 114, while it would be difficult and expensive to replace the water cooled clamping band 14.

As will be apparent from FIGS. 1 and 7, the opposite ends of the water cooled band 14 are welded or otherwise secured, directly to the outer rectangular shell 82 of the supporting arm 16. The shell 82 is formed with apertures 119 to provide for the flow of the cooling water, into and out of the opposite ends of the band 14 through the passages 88 and 90. The front ends of the passages 88 and 90 are closed by a front end wall 118. For greater strength, upper and lower reinforcing plates 120 and 122 are connected between the opposite end portions of the band 14. The plates 120 and 122 are preferably welded to the band and also to the upper and lower walls 124 and 126,of the rectangular outershell 82.

The electrode holder 10 is provided with power means for moving the contact shoe 20, relative to the clamping band 14. Such power means may take the form of the illustrated fluid power cylinder 130, preferably operable by compressed air. As shown, the cylinder 130 is coaxial with the actuating tube 22 and the inner shell or guide tube 80. Thus, the cylinder 130 is mounted around the actuating tube 22 and is mounted upon the end of the guide tube 80 and the rectangular outer shell 82.

The illustrated fluid power cylinder 130 comprises a cylindrical wall 132 having end flanges 134 and 136. The flange 134 is bolted or otherwise mounted to a flange 138, which forms the end wall for the inner and outer shells 80 and 82. The flange 138 is welded or otherwise secured to the shells'80 and 82.

The end plate 140 is bolted or otherwise secured to the flange 136. It will be seen that the plate 140has a clearance opening 142 for the actuating tube 22. I

An annular piston 144 is mounted within the cylindrical wall 132 to form the movable wall of the cylinder 130. A suitableseal 146 is provided between the piston 144 and the cylindrical wall 132. In this case, the piston 144 is welded or otherwise secured to the actuating tube 22. Thus, the actuating tube 22 and thecontact shoe 20 can be moved by compressed air, applied against the piston 144. The compressed air can be admitted to the cylinder through an inlet pipe 148, which connects with the cylinder on the left-hand side of the piston 144, as shown in FIG. 6.

The actuating tube 22 is movable through an opening 147 in the end plate 134. A suitable seal 149 is provided between the end plate 134 and the actuating tube 22.

It is preferred to utilize spring means to bias the contact shoe 20 against the electrode 12. With this construction, the electrode holder is fail safe, in that electrode 12 will be clamped by spring action when air pressure is not appliedto the cylinder 130. Thus, the electrode will never slip due to the loss of air pressure. Instead, the electrode will be tightly clamped if air pressure is lost.

In the illustrated construction, the piston 144 is biased to the left, in a clamping direction, by such spring means 150. It is preferred that the spring means 150 take the form of a plurality of Belleville springs, which comprise concave annular discs, interposed between the piston 144 and the end plate 140. It will be understoodthat springs of other types can be employed. The springs 150 are mounted around the actuating tube 22 and within the cylindrical wall 132. It will be apparent that the springs bias the actuating tube 22 and the contact 7 shoe 20 to the left, so that the shoe is pressed tightly against the electrode 12. The springs 150 are sufficiently strong to provide the desired clamping pressure. When the clamping pressure is to be released, air is-applied against the left-hand side of the piston '144 so as to compress the springs 150, while moving the shoe 20 to a slight extent away from the electrode 12. In this way, the electrode is allowed to slip downwardly to compensate for the consumption of the electrode in the electric furnace. The full clamping pressure is reapplied by the springs 150 when the air pressure is removed from the piston 144.

The electrical current is supplied by the cables 54 to the bus tube 24, and then to the contact shoe 20, which transfers the current to the electrode 12. The cooling water for the shoe 20 is circulated through the fittings 56. and 64 connected to the spaces within the bus tube 24 and the actuating tube 22. The water flows from the bus tube 24 into the shoe 20 through the central opening 42, and then, through the passages 44, 46 and 48 in the shoe to the outlet openings 50 which are disposed around a circle, opposite the space between the actuating tube 22 and the bus tube 24. It will be understood that the cooling water can be circulated in the opposite direction if desired.

The cooling water for the passages 106 in the clamping band 14 is circulated through the passages 88 and 90 (FIG. 4). These passages are formed between the cylindrical inner shell and the rectangular outer shell 82 of the supporting arm 16. The cooling water is supplied to the passages 88 and through the pipes 94 and 96. It will be understood that the cooling water may be circulated in either direction.

It will be seen from FIGS. 1 and 3 that mounting brackets 154 are welded or otherwise secured to the rectangular outer shell 82 of the supporting arm 16. These mounting brackets 154 may be employed to securethe electrode holder to a suitable support.

It will be recognized that the various components of the electrode holder are formed as a single unit. Thus, the clamping band 14 is welded directly to the supporting arm 16. Moreover, the power cylinder 130 is mounted on the supporting arm and around the actuating tube 22. Nevertheless, it is easy to service the cylinder 130. Moreover, the contact shoe 20 can readily be removed and replaced if necessary.

We claim:

1. An electrode holder for an electric furnace electrode,

comprising a clamping band adapted to extend around the electrode,

a movable contact shoe for engaging the electrode in opposition to said clamping band,

a supporting arm including an outer tubular member having one end connected to said band,

an actuating tube and a bus tube disposed in coaxial relation to each other and extending within said outer tubular member,

said actuating tube and said bus tube being connected to said contact shoe at one end of each of said tubes,

said shoe having coolant passages therein connected at one end to the inside of said actuating tube and at the other end to the inside of said bus tube,

means for circulating a coolant through said bus tube and said actuating tube to and from said contact shoe,

said bus tube being made of material having a low electral resistance for carrying electrical current to said shoe, means mounting said tubes for longitudinal movement within said outer tubular member,

and power means for moving said actuating tube whereby said shoe can be moved into and out of clamping engagement with the electrode.

2. An electrode holder according to claim 1, in which said bus tube is disposed coaxially within said actuating tube. 3 An electrode holder according to claim 2, including fittings connected to the inside of said 'bus tube and to the space between said actuating tube and said bus tube for circulating the coolant through said tubes. 4. An electrode holder according to claim 1, including electrical insulating means between said bus tube and said actuating tube. 5. An electrode holder according to claim 1, in which said bus tube is coaxially disposed within said-actuating tube with space therebetween to carry the coolant, said shoe having at least one port communicating with the inside of said bus tube, said shoe having a plurality of ports communicating with the space between said bus tube and said actuating tube, said coolant passages in said shoe radiating outwardly between said first-mentioned port and said second-men- 'tioned ports. 6. An electrode holder accordingto claim 1, in which said power means comprise a fluid power actuator connected between said outer tubular member and said actuating tube. 7 An electrode holder according to claim 1,

in which said power means comprise an annular fluid power cylinder mounted around said actuating member and connected to said outer tubular member,

said cylinder havingan annular piston movable therein and connected to said actuating member.

8. An electrode holder according to claim 7,

including a spring means connected between said cylinder and said piston for biasing the contact shoe into engagement with the electrode,

said piston being operable by-fluid pressure to release the clamping pressure between said shoe and the electrode.

9. An electrode holder according to claim 1,

in which said clamping band is formed with passageways for carrying a fluid coolant, I

said supporting arm having means for carrying the coolant to and from said passageways.

10. An electrode holder according to claim 1 in which said clamping band is formed with passageways for carrying a fluid coolant,

said outer tubular member comprising an outer shell of generally rectangular cross section and an inner shell of generally circular cross section received within said outer shell,

said inner and outer shells having openings there between for carrying the fluid coolant to and from the passageways in said clamping band.

1 1. An electrode holder according to claim 1,

in which said bus tube is coaxially disposed within said actuating tube with space therebetween to carry the coolant,

said shoe having at least one port communicating with the inside of said bus tube,

said shoe having a plurality of ports communicating with the space between said bus tube and said actuating tube,

said shoe having coolant passages radiating outwardly from said first-mentioned port and then turning inwardly to said second-mentioned ports.

12. An electrode holderfor an electric furnace electrode,

comprising a clamping band adapted to extend around the electrode,

a movable contact shoe for engaging the electrode in opposition to said clamping band,

and inner and outer tubes connected to said contact shoe for circulating a fluid coolant thereto,

said inner tube being disposed within said outer tube with space therebetween,

said shoe having at least one port communicating with the inside of said inner tube,

said shoe having a plurality of ports communicating with the space between said inner and outer tubes,

said shoe having coolant passages extending therein between said first-mentioned port and said second-mentioned ports.

13. An electrode holder according to claim 12,

in which said coolant passages radiate outwardly from said first-mentioned port.

14. An electrode holder according to claim 12,

in which said coolant passages radiate outwardly from said firsbmentioned port and then turn inwardly to said second mentioned ports.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 602,624 Dated August 31, 1971 Inventor(a) Alfred H. Turner and Lewis H. Durdin It is certified that errot appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

FBI

Column 5, line 28, Change "electral" to -electrical.

Signed and sealed this 25th day of January 1972.

(SEAL) Attest: A

EDWARD M'FLETCHERJR. ROBERT GOTTSCHALK Attesting Officer Commlssloner of Patents 

1. An electrode holder for an electric furnace electrode, comprising a clamping band adapted to extend around the electrode, a movable contact shoe for engaging the electrode in opposition to said clamping band, a supporting arm including an outer tubular member having one end connected to said band, an actuating tube and a bus tube disposed in coaxial relation to each other and extending within said outer tubular member, said actuating tube and said bus tube being connected to said contact shoe at one end of each of said tubes, said shoe having coolant passages therein connected at one end to the inside of said actuating tube and at the other end to the inside of said bus tube, means for circulating a coolant through said bus tube and said actuating tube to and from said contact shoe, said bus tube being made of material having a low electral resistAnce for carrying electrical current to said shoe, means mounting said tubes for longitudinal movement within said outer tubular member, and power means for moving said actuating tube whereby said shoe can be moved into and out of clamping engagement with the electrode.
 2. An electrode holder according to claim 1, in which said bus tube is disposed coaxially within said actuating tube. 3 An electrode holder according to claim 2, including fittings connected to the inside of said bus tube and to the space between said actuating tube and said bus tube for circulating the coolant through said tubes.
 4. An electrode holder according to claim 1, including electrical insulating means between said bus tube and said actuating tube.
 5. An electrode holder according to claim 1, in which said bus tube is coaxially disposed within said actuating tube with space therebetween to carry the coolant, said shoe having at least one port communicating with the inside of said bus tube, said shoe having a plurality of ports communicating with the space between said bus tube and said actuating tube, said coolant passages in said shoe radiating outwardly between said first-mentioned port and said second-mentioned ports.
 6. An electrode holder according to claim 1, in which said power means comprise a fluid power actuator connected between said outer tubular member and said actuating tube. 7 An electrode holder according to claim 1, in which said power means comprise an annular fluid power cylinder mounted around said actuating member and connected to said outer tubular member, said cylinder having an annular piston movable therein and connected to said actuating member.
 8. An electrode holder according to claim 7, including a spring means connected between said cylinder and said piston for biasing the contact shoe into engagement with the electrode, said piston being operable by fluid pressure to release the clamping pressure between said shoe and the electrode.
 9. An electrode holder according to claim 1, in which said clamping band is formed with passageways for carrying a fluid coolant, said supporting arm having means for carrying the coolant to and from said passageways.
 10. An electrode holder according to claim 1, in which said clamping band is formed with passageways for carrying a fluid coolant, said outer tubular member comprising an outer shell of generally rectangular cross section and an inner shell of generally circular cross section received within said outer shell, said inner and outer shells having openings there between for carrying the fluid coolant to and from the passageways in said clamping band.
 11. An electrode holder according to claim 1, in which said bus tube is coaxially disposed within said actuating tube with space therebetween to carry the coolant, said shoe having at least one port communicating with the inside of said bus tube, said shoe having a plurality of ports communicating with the space between said bus tube and said actuating tube, said shoe having coolant passages radiating outwardly from said first-mentioned port and then turning inwardly to said second-mentioned ports.
 12. An electrode holder for an electric furnace electrode, comprising a clamping band adapted to extend around the electrode, a movable contact shoe for engaging the electrode in opposition to said clamping band, and inner and outer tubes connected to said contact shoe for circulating a fluid coolant thereto, said inner tube being disposed within said outer tube with space therebetween, said shoe having at least one port communicating with the inside of said inner tube, said shoe having a plurality of ports communicating with the space between said inner and outer tubes, said shoe having coolant passages extending therein between said first-mentioned port and said second-mentioned ports.
 13. An electrOde holder according to claim 12, in which said coolant passages radiate outwardly from said first-mentioned port.
 14. An electrode holder according to claim 12, in which said coolant passages radiate outwardly from said first-mentioned port and then turn inwardly to said second mentioned ports. 